Monday, May 28, 2012

After the Japan Nuclear Energy Safety Organization (JNES) published its analysis that the water level inside the Containment Vessel of Reactor 1 at Fukushima I Nuclear Power Plant may be only 40 centimeters deep, TEPCO announced the plan to probe inside the Containment Vessel with the endoscope, just as they did for Reactor 2.

According to Jiji Tsushin, TEPCO plans to visually inspect the inside (by two endoscopic cameras), take temperature and radiation measurements, and collect the water samples near where the fuel debris (corium) is supposed to be on the floor of the Containment Vessel.

Toward decommissioning Fukushima I Nuclear Power Plant, the plan has been agreed upon to probe the interior of the Reactor 1 Containment Vessel using the industrial endoscope and collect the sample of highly contaminated water near the fuel debris for analysis. The work will be carried out sometime between late August and mid September.

...

格納容器内部の調査は今年１、３月に２号機で行われ、水位が底から約６０センチしかないと判明している。

The probe of the Containment Vessel interior was done on Reactor 2 in January and March this year, which revealed the water level to be only 60 centimeters from the floor of the Containment Vessel.

In Reactor 1, TEPCO will insert the camera and radiation survey meter through one of the spare penetrations for the pipes, and collect the contaminated water and analyze in order to estimate the condition of the melted fuel. After the probe, a thermocouple will be left inside the Containment Vessel [in the water] to continuously measure the temperature of the water.

The details of the Reactor 1 CV probe are in one of the reference materials (Japanese-only; pages 18 to 25) for the May 28, 2012 meeting of the Working Group for Medium to Long Term Planning. TEPCO will have to build a mock-up first to train the workers. (I'll post some of the pages here later.)

The fast erosion phase of the concrete basemat lasts for about an hour and progresses into about one meter depth, then slows to several centimeters per hour, and stops completely when the melt cools below the decomposition temperature of concrete (about 1100 °C). Complete melt-through can occur in several days even through several meters of concrete; the corium then penetrates several meters into the underlying soil, spreads around, cools and solidifies.

@laprimavera: Many thanks for the info and explanation. And my apologies. Am on a slow broadband connection these days with pictures turned off on web sites, so I completely missed the obvious details. Sorry about that.*mscharisma*

Don't worry about melting through in Fukushima, this is practically impossible.

Better let's hope that French Hollande will keep his promise to turn off Fessenheim power plant at the Rhine, located directly at the German border. Remember, Fessenheim reactor's concrete thickness is 1.5 meters compared with the about 10 meters at Fukushima. If an accident occurs there, the Netherlands would be in a very bad situation, as they rely mainly on the Rhine for their water supply.

@ LaPrimavera

Thank you, I actually missed this interesting fact that these radiation maps just blank out the lesser "inviting" areas making #1 look way cleaner than it is. One really has to look very careful at what Tepco presents.

About my coverage of Japan Earthquake of March 11

I am Japanese, and I not only read Japanese news sources for information on earthquake and the Fukushima Nuke Plant but also watch press conferences via the Internet when I can and summarize my findings, adding my observations.

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Well, this was, until March 11, 2011. Now it is taken over by the events in Japan, first earthquake and tsunami but quickly by the nuke reactor accident. It continues to be a one-person (me) blog, and I haven't even managed to update the sidebars after 5 months... Thanks for coming, spread the word.------------------This is an aggregator site of blogs coming out of SKF (double-short financials ETF) message board at Yahoo.

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